Readily accessible in vitro neuronal cells and populations of required identity are crucial in a number of applications, e.g., in the study of the normal physiological behaviour of the respective neuronal types, in the study of the aetiology of neurological or neuropsychiatric disorders, in neuron-replacement therapies of neurological diseases, or in various cell-based assays of pharmacological, toxicological or other agents, etc.
In particular, cultured cortical and striatal neurons would aid in deciphering the normal development, structure and physiology of the cerebral cortex and basal ganglia, as well as allow to generate representative models of, and cell screening platforms for, widespread cortical afflictions, including Alzheimer's disease, Huntington's disease, stroke or epilepsy. However, to date robust and simple methods are not available to derive cortical neurons readily and consistently from mature or embryonic brain tissue, nor from other cell sources.
Hence, there exists a need in the art to provide straightforward methods that can reproducibly generate in vitro neuronal populations representative of the cerebral cortex or the striatum. Preferably, said methods may depart from a comparably well-characterised and accessible cell source. The resultant in vitro neuronal cultures may comprise, and preferably be significantly enriched in, any one or both of the basic cortical neuronal types including pyramidal neurons and inhibitory interneurons. More particularly, said neuronal cultures may also display further levels of neuronal specialisation or differentiation within any of said basic cortical neuronal types, as evidenced by, for example, differences in morphology, marker expression, electro-physiology, etc.
Ying et al. 2003 (Nat Biotechnol 21: 183-6) reported that in adherent monoculture of mouse embryonic stem (ES) cells (i.e., without the formation of embryoid bodies in suspension culture, and without co-culture of ES cells with non-ES cells), elimination of inductive signals for alternative cell fates sufficed for a bulk of the ES cells to develop into neural precursors. However, these authors did not address whether said neural precursors were able to generate cortical neuronal subtypes such as pyramidal cells or interneurons, or striatal neurons, or to emulate cortical cell type development, and thus also did not disclose any conditions to achieve such cortical differentiation.